import React from 'react'
import { useState } from 'react'
import B from "./B"

//1. 创建上下文对象
export let countContext = React.createContext();

export default function A() {
    let [count,setCount] = useState(100);
    return (
        <div>
            {/* 2. 将后代组件全部包裹在 Provider 组件中   value={count}  */}
            <countContext.Provider value={[count,setCount]} >
                <h1>这是A组件: {count}  </h1>
                <B></B>
            </countContext.Provider>
        </div>
    )
}
